1. Field of the Invention
The present invention relates to a fuel injection valve used for injecting fuel to an automotive engine and the like.
2. Description of the Related Art
Japanese Patent Unexamined Publication No. P2000-8990A (2000008990) describes a fuel injection valve which is used for an automotive engine and the like. Generally, a valve casing of the fuel injection valve is made of magnetic metal material and the like, and is shaped substantially into a tube. A valve body of the fuel injection valve is displaceably inserted in an inner periphery of the valve casing. In an operation period of the fuel injection valve, a magnetic field generated by an electromagnetic coil may act on the valve body by way of the valve casing, thereby opening the valve body magnetically.
It is an object of the present invention to provide a fuel injection valve with accuracy in fuel injection amount improved by stabilizing stroke of a valve body, wherein stabilization of the stroke is effected by a general mechanical machining on a core tube.
According to the present invention, there is provided a fuel injection valve, comprising: a tubular body, a valve seat member, a valve body, a core tube, a bias spring, and an electromagnetic actuator. The tubular body is made of a magnetic material and formed substantially into a tube. The tubular body has a first end side and a second end side opposite to the first end side. The valve seat member is disposed on the first end side of the tubular body. The valve seat member is formed with a fuel injection port and a valve seat surrounding the fuel injection port. The valve body is displaceably disposed in the tubular body. The valve body has a first end side defining a valve section which is detachably seated on the valve seat of the valve seat member. The valve body has a second end side, which is opposite to the first end side thereof, defining an absorption section. The core tube is press fitted into the tubular body. The core tube has a first end side opposing the absorption section of the valve body in such a manner as to form an axial gap interposed between the first end side of the core tube and the absorption section of the valve body. The core tube has a second end side axially extending in the tubular body to a certain position on a way to the second end side of the tubular body. The axially extending second end side of the core tube has an outer periphery which is formed with a reduced diameter section for increasing an accuracy in positioning the core tube when the core tube is press fitted into the tubular body. The bias spring is disposed in the tubular body, and biases the valve body in a direction for closing the valve body. The electromagnetic actuator is disposed at the tubular body. The electromagnetic actuator forms a magnetic field between the absorption section of the valve body and the core tube so as to allow the valve body to open opposing the bias spring.
The other objects and features of the present invention will become understood from the following description with reference to the accompanying drawings.